Hi Rookie84,
First of all, a 690 is a great start! Based on the score breakdown of your exam, you are weaker in verbal than quant. Thus, you may consider focusing the majority of your study efforts on verbal (perhaps a 3 to 1 ratio of verbal to quant.)
When studying for your retake, you must keep in mind that the GMAT such a challenging exam is that there are relatively few questions asked in a given exam, yet those questions come from a huge topic pool. Thus, the best way to get a great GMAT score is to have a thorough understanding of all the topics that may be tested on the exam. To develop such mastery, you want to strive for linear and targeted learning and follow that with focused practice. In other words, you want to master one topic before you move to the next. Have you been able to study in this way?
For example, when studying verbal, focus on learning one section at a time: reading comprehension, sentence correction, or critical reasoning. When learning about critical reasoning, you want to be able to learn about all aspects of critical reasoning: strengthen and weaken the conclusion, resolve the paradox, find the conclusion, must be true, etc. Follow up your learning with focused critical reasoning practice, so you can determine your specific weaknesses within that topic. You should follow a similar routine for sentence correction and reading comprehension.
Also, to help improve your reading comprehension, I recommend reading publications such as the Economist, the New Yorker,Scientific American, or the Smithsonian so you can get used to reading and analyzing long, sophisticated passages that are well written.
To truly master sentence correction, you must develop mastery of grammar rules (parallelism, subject/verb agreement, etc.) and accepted English usage. In addition to your dedicated study, notice grammar and usage in your everyday life. Be aware of the things you habitually read, in terms of sentence structure, how phrases are worded, and whether pronouns are easy to understand. Make sure you use proper grammar in your everyday writing as well. Have you put parallel ideas into parallel constructions? Do all of your pronouns refer appropriately to their antecedents? The more you reinforce your study with related activity outside of your study, the greater the likelihood you will master the topics, and have fun doing so!
For quant, since you scored a 48 on your GMAT, you might consider following a similar but slightly altered approach that consists of more focused practice. For example, if you are reviewing number properties, be sure that you can practice 50 or more questions just from Number Properties: LCM, GCF, units digit patterns, divisibility, remainders, etc. The results of that practice will help you determine your weak areas within that topic. Once you find and fix your weak areas, then move on to the next quant topic.
Also, I see that for your initial GMAT you studied a lot with
the Official Guide. While
the Official Guide is a great book because it has official questions from past GMATs, it has limited instruction and does not provide full exposure to all GMAT topics. Thus, for your retake, you may consider seeking out some robust prep materials that provide sufficient targeted practice for you to discover and fix your weak areas.
If you have any further questions, feel free to contact me directly.